1. Field of the Invention
The present invention relates to a method and an apparatus for adjusting the contact force between two frictionally-engaged components of a drive system. More particularly, the present invention relates to a method and a control apparatus for a drive system having components that are frictionally driven to transmit torque, for example by an endless torque-transmitting means that frictionally transmits torque between pairs of conical disks of a continuously variable transmission, in which the transmission ratio can be steplessly changed, and that enables adjustment of the contact force between the frictionally-engaged components.
2. Description of the Related Art
Frictionally-engaged torque-transmitting assemblies included in the drive train of a motor vehicle, such as clutches, including converter lock-up clutches in the torque converter of an automatic transmission, continuously variable transmission ratio transmissions incorporating endless torque-transmitting means (e.g., continuously variable transmissions, friction wheel transmissions), and also brakes, are being increasingly automated or operated by their own actuators. The control or regulation of the torque that is frictionally-transmitted by a particular assembly should be as low as possible to unburden the actuators, as well as for lower energy consumption and higher control or regulation accuracy, yet high enough to avoid permanent slippage that could lead to rapid wear or destruction of the components that frictionally transmit the torque. A precise adjustment of the torque-transmitting capacity between two frictionally-engaged torque-transmitting components and/or an exact adjustment of the contact force between two frictionally-engaged torque-transmitting components is accordingly of great significance.